laconicd/docs/guides/truffle.md

Truffle

Set up a Truffle Ethermint local development environment. {synopsis}

Pre-requisite Readings

• Installation {prereq}
• Run a node {prereq}

Truffle is a development framework for deploying and managing Solidity smart contracts. In this guide, we will learn how to deploy a contract to a running Ethermint network.

Install dependencies

First, install the latest Truffle version on your machine globally.

npm install truffle -g

You will also need to install Ethermint. Check this document for the full instructions.

Create Truffle Project

In this step we will create a simple counter contract. Feel free to skip this step if you already have your own compiled contract.

Create a new directory to host the contracts and initialize it

mkdir ethermint-truffle
cd ethermint-truffle

Initialize the Truffle suite with:

truffle init

Create contracts/Counter.sol containing the following contract:

pragma solidity ^0.5.11;

contract Counter {
  uint256 counter = 0;

  function add() public {
    counter++;
  }

  function subtract() public {
    counter--;
  }

  function getCounter() public view returns (uint256) {
    return counter;
  }
}

Compile the contract using the compile command:

truffle compile

Create test/counter_test.js containing the following tests in Javascript using Mocha:

const Counter = artifacts.require("Counter")

contract('Counter', accounts => {
  const from = accounts[0]
  let counter

  before(async() => {
    counter = await Counter.new()
  })

  it('should add', async() => {
    await counter.add()
    let count = await counter.getCounter()
    assert(count == 1, `count was ${count}`)
  })
})

Truffle configuration

Open truffle-config.js and uncomment the development section in networks:

    development: {
     host: "127.0.0.1",     // Localhost (default: none)
     port: 8545,            // Standard Ethereum port (default: none)
     network_id: "*",       // Any network (default: none)
    },

This will allow your contract to connect to your Ethermint local node.

Start Node and REST server

Start your local node using the following command on the Terminal

# on the ~/ethermint/ directory
init.sh

::: tip For further information on how to run a node, please refer to this quickstart document. :::

In another Terminal wintdow/tab, start the REST and JSON-RPC server:

emintcli rest-server --laddr "tcp://localhost:8545" --unlock-key mykey--chain-id 8 --trace

Deploy contract

Back in the Truffle terminal, migrate the contract using

truffle migrate --network development

You should see incoming deployment logs in the Ethermint daemon Terminal tab for each transaction (one to deploy Migrations.sol and the oether to deploy Counter.sol).

I[2020-07-15|17:35:59.934] Added good transaction                       module=mempool tx=22245B935689918D332F58E82690F02073F0453D54D5944B6D64AAF1F21974E2 res="&{CheckTx:log:\"[]\" gas_wanted:6721975 }" height=3 total=1
I[2020-07-15|17:36:02.065] Executed block                               module=state height=4 validTxs=1 invalidTxs=0
I[2020-07-15|17:36:02.068] Committed state                              module=state height=4 txs=1 appHash=76BA85365F10A59FE24ADCA87544191C2D72B9FB5630466C5B71E878F9C0A111
I[2020-07-15|17:36:02.981] Added good transaction                       module=mempool tx=84516B4588CBB21E6D562A6A295F1F8876076A0CFF2EF1B0EC670AD8D8BB5425 res="&{CheckTx:log:\"[]\" gas_wanted:6721975 }" height=4 total=1

Run Truffle tests

Now, you can run the Truffle tests using the Ethermint node using the test command:

truffle test --network development

Using network 'development'.


Compiling your contracts...
===========================
> Everything is up to date, there is nothing to compile.



  Contract: Counter
    ✓ should add (5036ms)


  1 passing (10s)

Next {hide}

Learn how to connect Ethermint to Metamask {hide}